Apple /// was 2MHz and it was a disaster.
I wouldn't call it a disaster, sales and marketing wise mainly, but that also had a lot to do with the IBM PC coming out around the same time.
It was probably the most complex 6502 design, and mainly consisted of discrete logic chips rather than custom chips that other manufactures were starting to use. It had advanced features like an additional addressing mode to access up to 512k RAM without bank switching. (Plus two speed arrow keys)
It overheated, unseated chips, had a non-functional clock chip and other kinds of terrible quality controls. It also had to compete against the IBM PC while Apple still didn’t even had added lowercase input to their II+.